The adverse health consequences and growing prevalence of obesity are major health concerns in the U.S. today. Recognition of the involvement of genetic factors in obesity reaffirms the importance of animal models, such as the Zucker fatty rat, for analyzing antecedent conditions promoting the obese state. Using a concurrent behavioral and metabolic approach, the proposed research analyzes the relation between the fatty rat's chronic lipogenic profile and its altered feeding behavior throughout development. The goal of this research is to identify feeding stimulatory and inhibitory factors that arise from adipose tissue, and to utilize this information in dietary and pharmacologic manipulations that may attenuate the development of obesity. Specifically, this research examines the role of adipocyte enlargement in promoting the characteristic hyperphagia of developing male fatty rats, and, via new studies of adipocyte proliferation in female fatty rats, seeks to define potential differences in the role of adipose tissue in promoting male vs female obesity. In addition, this research will evaluate the effectiveness of metabolic agents in altering excess lipid deposition and increased feeding behavior in developing fatty rats. Finally, biochemical studies will be carried out in adult fatty rats to probe the nature of feeding inhibitory signals arising from enlarged fat cells, and the conditions under which such factors are activated. The results of this research should provide specific information on feeding stimulatory and inhibitory influences arising from adipose tissue, of potentially crucial value in the design of effective intervention and treatment strategies for obesity, a disease that has been highly resistant to corrective attempts.